Wednesday, April 06, 2005

Nutrition Basics - Cholesterol

Olive oil

Cholesterol is not the same thing as cooking fats or fats found in the body, but is a fat-related compound. Cholesterol is a sterol, a subcategory of lipids (the scientific name for all substances commonly known as fat). There are two types of cholesterol: dietary and serum. Dietary cholesterol does not exist in any plant foods; it is found only in animal foods. Serum, or blood, cholesterol is found in the bloodstream and is essential to life.

The liver manufactures about 1,000 milligrams of serum cholesterol daily, which is used to provide a fatty protective jacket around nerve fibers. In the skin, a derivative of cholesterol is made into vitamin D with the aid of sunlight. Cholesterol also functions in the outer membranes of the cells and as a building block for certain hormones. It is not essential to consumer cholesterol, because humans are capable of producing it from other dietary components. Furthermore, foods high in cholesterol also tend to have higher amounts of fat. For these reasons, it is recommended that daily dietary cholesterol should not exceed 300 milligrams, regardless of how many calories are consumed.

Cholesterol is transported by two main types of proteins in the blood, high-density lipoproteins (HDL) and low-density lipoproteins (LDL). LDL takes cholesterol into the circulatory system, and HDL clears cholesterol out of the circulatory system. A high level of HDL is desirable because it usually indicates a reduced risk of heart disease. LDL is a sticky substance that tends to deposit cholesterol in areas of high blood flow, such as arterial walls, these deposits may build up and eventually block the arteries so that blood cannot flow easily, causing a condition called atherosclerosis. Such a condition can lead to aneurysms, coronary and cerebral thrombosis, embolism, heart attack, and stroke.

The consumption of saturated fat has been shown to raise the level of LDL in the blood more than the consumption of dietary cholesterol. It is for this reason that health experts recommend limiting saturated fat to less than 10 percent of daily caloric intake.
The Professional Chef, 7th Edition by The Culinary Institute of America

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